Field of the Invention
This invention relates generally to an apparatus for dislodging accumulated bulk material from surfaces of bulk material handling devices, such as kilns used in the cement and paper industries. More particularly, the invention relates to an apparatus comprising an air cannon portion and a sonic horn portion. The invention also pertains to a sonic horn having a unique sound outlet passageway configuration.
General Background
Air cannons are commonly used in the bulk material handling industry for dislodging accumulated bulk material deposits from surfaces of bulk material handling devices, such as kilns, hoppers, and transfer chutes. Sonic horns are also used to dislodge accumulated bulk material and/or prevent bulk material from accumulating. If not dislodged, such accumulated bulk material can interfere with operation of such bulk material handling devices.
Air cannons are comprised of a pressure vessel, a discharge valve, and a discharge passageway. The pressure vessel is periodically filled with pressurized gas, such as air, from a pressurized gas source. When the discharge valve is actuated, typically via gas pressure, the stored compressed gas in the pressure vessel escapes from the pressure vessel and is discharged into the discharge passageway. This process occurs very abruptly and converts the stored potential energy of the compressed gas into kinetic energy. The gas escapes from the gas passageway through an outlet, typically at supersonic speeds. The resulting blast of gas transfers much of its energy to the accumulated bulk material and thereby dislodges the accumulated bulk material from surfaces. Although the compressed gas is typically air, other gases such as nitrogen or carbon-dioxide are also sometimes used. Regardless of the composition of the gas, such a device is commonly and herein referred to as an air cannon.
Sonic horns, as they are known in the industry, are also commonly used for dislodging accumulated bulk material from surfaces of bulk material handling devices or preventing the accumulation thereof. A sonic horn generally comprises a sound generator and a sound passageway that directs and focuses the sound waves generated by the sound generator. Typically, the sound generators of sonic horns are activated periodically and are powered electrically or, more commonly, pneumatically. The sound waves generated by sonic horns are typically low frequency (less than 300 Hz) and high amplitude (120-145 dB). However, sonic horns are often configured to emit frequencies and amplitudes of sound that best resonate the bulk material within a particular bulk material handling device, and frequencies may be magnitudes higher. As a result of the vibrations, the structural bonds that have been formed between the accumulated bulk material itself and the surfaces of the bulk material handling device are broken, and the accumulated bulk material is dislodged. Similarly, the vibrations inhibit the accumulation of bulk material on the surfaces of the bulk material handling device.
Individually, air cannons and sonic horns each are advantageous in some regards and disadvantageous in others. For example, while air cannons are good at dislodging heavy buildup of accumulated bulk material, they do little to prevent such accumulation from occurring between the blasts of compressed gas. Conversely, although sonic horns are good at loosening bonds between accumulated bulk material particles and preventing such bonds from occurring, they are less effective when the bulk material accumulation is relatively thick. As a result of these strengths and weaknesses, air cannons and sonic horns are sometimes used in combination. However, doing so increases costs and complexity.